BACKGROUND OF THE INVENTION The present invention relates to fluid storage and transport tanks, and in particular, to a method and apparatus of sealing ruptured leaks and thereby substantially preventing leakage. A major problem in the storage and transport of fluids, such as gases, volatile liquids or liαuids which may cause damage to the environment is that if ruptures or splits occur in the tanks containing the fluid, it has been found that it is very difficult to prevent the leakage of further fluid from the tank. These fluids may then escape from the tank and contaminate ecologically Important areas, for example by liquids flowing through drainage systems and thus these areas may be damaged.

This is particularly the case in relation to transport vehicles which are known as road tankers or with sea-going oil tankers. If a tanker is involved in a motor vehicle accident, it has been found that the leakage of the fluids into the environment is not easily prevented. In the case of such accidents, the most prevalaπt type of rupture is that a split occurs in the tank generally adjacent baffles located in the tank. Known ways of preventing or stopping such leakages is by using wooden pegs to bung the rupture. In many such instances the use of a wooden peg is inappropriate.

Likewise, in fluid storage tanks, if a rupture occurs for any reason, there is no suitable method or apparatus to stem the leakage of the liquid contained in the storage tank. In the case of sea-going oil tankers there has been in recent times a spate of damaging oil leaks due to ruptured hulls. Damage to the environment is great and there are no satisfactory methods of plugging the leaks.

In patent specification W086/06039, an apparatus is described which comprises a shape adjustable patching element which is first welded to the tank when repairs are being conducted. A mattress or annular shaped bag is then filled with gas, liquid or solidified material in order that the leak in the tank be sealed. This apparatus is cumbersome to use anc is not readily applicable to either road tankers or sea-going oil tankers. In patent SDecifi cation WO87/02650, an apparatus is described which includes a vacuum leak sealing pad which uses a vacuum to secure the pad to a tank wall. However, such an aDparatus is also cumoersomε and ciffic lt to use anc is net readily aπciicable for leaκs in ro c tan er: cr sε -coinc: c-i • tanters.

BRIEF SUMMARY OF THE INVENTION It is an object of the -present invention to provide an apparatus and method of sealing ruptured tanks which substantially overcomes or ameliorates the abovementioned disadvantages. According to one aspect of the present invention there is disclosed apparatus for substantially sealing a rupture in a fluid storage or transport tank, said apparatus comprising a flexi-Me, substantially rigid backing plate, fastening means attached to the backing plate for attaching the backing plate to said tank, and a resilient layer adjacent the backing plate for positioning over the rupture, wherein said resilient layer is compressed against the rupture to substantially reduce the flow of leaking fluid therefrom when the backing plate is attached to the tank.

In a preferred embodiment, the fastening means comprises at least one contact face for attachment to the tank. Preferably the contact face(s) is/are nearer the backing plate than a contact surface of the resilient layer, whereby the resilient layer is compressed between the backing plate and the tank when the contact face(s) is/are brought into contact with the tank. Preferably, a plurality of similar fastening means are provided at spaced intervals along the periphery of the backing pl te.

Preferably, the resilient layer is, or includes a layer of material which is, impervious to the fluid contained in the tank. For example, materials which are suitable for oil leaks, as they are impervious to oil Include many types of plastics and include Thurban (manufactured by

Bayer), Chemoline (manufactured by Stahlgruber)and Viton (manufactured by Du Pont).

The resilient layer is preferably formed of sponge rubber, plastics material, such as polyurethane, a quasi-plastics material of the type that liquifies when under pressure but then solidifies again, such as

Sorbothane, or any other suitable material. The resilient layer can, for example comprise a bladder filled with gas, e.g. air. liquid or material which solidifies in the bladder, and the bladder is preferably partly inflated or filled before being applied to the rupture with the amount of inflation being varied, usually increased, after application to the tank.

Another preferred feature is that the fastening means comprises magnetic means when the tank is made of steel, and suction means when tne tan is maαe of a non-ferrous material. The magnetic means can be of any type, for example metallic, ceramic, rare-earth cr electro- magnets. Tne

suction means is preferably of the suction cap type, but other types of vaccuum fastening means could be used. In some cases, an adhesive could be used as the fastening means. For example, some pressure, or impact, adhesives will displace oil from the contact area if applied quickly. Another preferred feature is that the backing plate can be constructed of a flexible material having corrugations to provide strength to the plate when the plate is of a large size. The plates have connection means in order that two or more plates can be combined to form a larger sized apparatus when required. The backing plate is preferably provided with a longitudinal clip along each longitudinal edge thereof, which clip can cooperate with a similar clip on another backing plate to hold the two plates together to form a larger apparatus. Preferably also, the transverse ends of the backing plate are shaped so as to facilitate abutment of two such plates together. It will be appreciated that larger ruptures can be sealed by joining or abuting a number of such plates together.

The flexible backing plate can be of any suitable flexible, rigid material, for example, aluminium, stainless steel or various types of plastics. According to a second aspect of the present invention, there is provided a method of sealing a rupture 1n a fluid storage or transport tank, the method comprising the steps of applying to said tank over the rupture an apparatus comprising a flexible, substantially rigid backing plate, fastening means attached to the backing plate for attaching the backing plate to said tank, and a resilient layer adjacent the backing plate for positioning over the rupture, and fastening the backing plate to the tank using the fastening means to thereby compress the resilient layer against the rupture to substantially reduce the flow of leaking fluid therefrom. BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present invention will now be described, by way of example, with reference to the drawings, in wnicπ:

Fig. 1 is an underside plan view of the apparatus of one preferred embodiment; Fig. 2 is a side view of the apparatus of Fig. 1;

Fig. 3 is a perspective view of the apparatus of a second embodiment;

Fig. 4 s a side view, similar to that of F ^; g. 2, of a r. ^* ^ e Dodiment;

Fig. 5 is a side elevational view through a fourth embodiment applied to a storage tank; and

Fig. 6 is a schematic view of a fifth embodiment of an apparatus according to the Invention. The apparatus 1 of the preferred embodiment shown in the drawings includes an aluminium plate 2 onto which a sponge rubber layer 3 is bonded. The sponge rubber layer has an impervious skin 4 which is impervious to the liquids contained in a transport tanker or tank ⁽ not illustrated) naturally, the type of impervious skin 4 is selected for each type of liquid which is either stored or transported.

Shown at the periphery of the plate 2 are a set of eight permanent magnets 5 which are also bonded to the aluminium plate. The sponge rubber layer 3 and the impervious skin 4 are both cut out around the each of the magnets 5 to allow the magnets to contact the tank, when applied thereto. As seen in Fig. 2, the height of the permanent magnets 5 is slightly less than that of the sponge rubber layer when the apparatus 1 is not in use.

When a rupture occurs in a tank or transport tanker made of steel or another ferrous material the apparatus 1 is able to be used to stem the flow of the leak. The permanent magnets are fastened to the steel tank and the sponge rubber layer 3 Is slightly compressed to thereby substantially seal the rupture. The flexible nature of the aluminium plate 2 allows the apparatus to be bent according to the shape of the tank where the rupture occurred. The use of the apparatus 1 of the preferred embodiment is used as a patching operation to prevent leakage or spillage of liquids into the environment following the rupture. Naturally, the tank will have to be emptied before major repairs can be made if indeed repairs are able to be carried out. The embodiment illustrated in Fig. 3 Includes apparatus 11 which includes a sheet 12 of material with a plurality of corrugations 13 located along the length to provide extra strength. In the drawing the corrugations are illustrated as only one type, obviously different types of corrugations could be used to provide the extra strength and rigidity. Along the peripheries 14 of the longitudinal sides a lip 15 located on one side is able to be clipped into a connection with a clip 16 which is located on the ohter side of another sheet 12. In this way a plurality of sheets 12 can be joined to form a larger apparatus i ^~ tne rupture is large anσ not able to be sealed by a single sheet 11.

The permanent magnets and sponge rubber layer are of a similar nature to that of the first described embodiment, and the apparatus 11 is therefore used in a similar manner.

In the case where the apparatus 11 is to be used to seal a leak on a sea-going oil tanker, the apparatus would - _* be placed into the water and applied by underwater divers. The plurality of apparatus are connected prior to being placed in the water but this is not necessarily so.

The embodiment shown in Figure 4 is similar to that of Figures 1 and 2, with similar elements having similar reference numerals. In this embodiment, however, the ends of the backing plate 2, resilient layer 3 and impervious skin 4 are cut in a step-like arrangement 6 across the thickness- thereof. In this way two similar apparatus can be easily coupled together in a cooperating manner with one end having a male arrangement and the other end having a female arrangement so that one such apparatus can be easily abutted against another such apparatus end to end. In this way, a larger rupture can be sealed, than a single apparatus could manage. Obviously, although only a stepped male and female arrangement 1s shown in Figure 4, other designs, such as, for example a tab and recess arrangement, could alternatively be used. Furthermore, although the stepped arrangement has been shown at the ends of the respective apparatus, similar arrangements could be provided at the side edges of the apparatus.

Of course, the resilient layer could be formed of a material inherently impervious to the fluid 1n the tank to be sealed, so that a separate impervious skin Is not required. Furthermore, rather than providing arcuate cutouts 1n the resilient layer around each magnet 5, the resilient layer could be simply arranged to have a width smaller than the spacing between magnets on opposite sides of the backing plate 2. Figure 5 shows an example of an apparatus according to another embodiment of the invention applied to a rupture 7 in a tank 8 close to an edge thereof. In such a case, the embodiments of Figures 1 to 3 could not be easily utilised as the magnets along one edge if the apparatus would not be fastened to the tank. Therefore, this embodiment uses a cantilever arrangement where two, or if necessary more, rows of magnets 5 are arranged side by side attached to the backing plate 2 and the resilient material, for example sponge rubber 3 having an impervious skin 4, is attached to the backing plate along a periphery thereof. This allows the resilient layer to be positioned adjacent the rupture 7 and

compressed against the tank 8 by the backing jjlate 2 when the magnets 5 are fastened to the side of the tank 8.

Finally, in Figure 6 there is shown a still further embodiment of an apparatus according to the invention for sealing ruptures around or very close to internal corners of a tank 8. In this case, the backing plate 2 is bent longitudinally along the centre thereof at an angle appropriate to the angle of the internal corner to be sealed. The magnets 5 and resilient layer are then attached to the outside of the bent backing plate in a similar manner to that described above so that the resilient layer will be compressed Into the -internal corner of the tank 8 when the magnets are attached thereto.

It will be apparent that alternative configurations of the apparatus can easily be provided in order to seal different configurations of the tank. For example, an apparatus for sealing a rupture at or close to an external corner could be provided similar to that described above, but with the backing plate 2 being bent in the opposite direction.

The foregoing describes only a few embodiments of the present invention, and modifications obvious to those skilled in the art can be made thereto without departing from the scope of the present invention. For example, the use of permanent magnets 5 as the fastening means to the tank can be replaced by suction devices when the tank 1s a non-ferrous material. In the case of an aluminium tank, the suction devices, such as used when handling glass panels can be used. These suction devices use a vacuum to create the fastening.

It 1s also obvious that the aluminium plate 2 and sponge rubber layer 3 can be replaced by similar materials which carry out the same function. The plate 2 can be made of another similar flexible material in order that the contour of the tank be matched. It is envisaged that a tanker would carry a number of the apparatus

1 of the present invention in order that the apparatus is able to be used for a number of different type ruptures in the tank.

It is also envisaged that the permanent magnets can be replaced or supplemented by a plurality of electromagnets which can be activated after placing the apparatus against the tanker.